Isolation of a novel adenovirus from Rousettus leschenaultii bats from India.

Surveillance work was initiated to study the presence of highly infectious diseases like Ebola-Reston, Marburg, Nipah and other possible viruses that are known to be found in the bat species and responsible for causing diseases in humans. A novel adenovirus was isolated from a common species of fruit bat (Rousettus leschenaultii) captured in Maharashtra State, India. Partial sequence analysis of the DNA polymerase gene shows this isolate to be a newly recognized member of the genus Mastadenovirus (family Adenoviridae), approximately 20% divergent at the nucleotide level from Japanese BatAdV, its closest known relative.

L-beta-(2S,4S)- and L-alpha-(2S,4R)-dioxolanyl nucleosides as potential anti-HIV agents: asymmetric synthesis and structure-activity relationships.

In order to study the structure-activity relationships of L-(2S,4S)- and L-(2S,4R)-dioxolanyl nucleoside as potential anti-HIV agents, various enantiomerically pure L-(2S,4S)- and (2S,4R)-dioxolanylpyrimidine and -purine nucleosides have been synthesized and evaluated against HIV-1 in human peripheral blood mononuclear (PBM) cells. The enantiomerically pure key intermediate 8 has been synthesized in six steps from 1,6-anhydro-beta-L-gulose (2), and compound 8 was condensed with 5-substituted pyrimidines, 6-chloropurine, and 2,6-disubstituted purine to obtain various dioxolanylpyrimidine and -purine nucleosides, respectively. Among the compound synthesized, 5-fluorocytosine derivative 29 was found to exhibit the most potent anti-HIV activity (EC50 = 0.0012 microM) although it was toxic (IC50 = 10.0 microM). The order of anti-HIV potency of pyrimidine analogues was as follows: 5-fluorocytosine (beta-isomer) > cytosine (beta-isomer) > 5-fluorocytosine (alpha-isomer) > 5-iodocytosine (beta-isomer) > cytosine (alpha-isomer) > 5-bromocytosine (beta-isomer) > thymine (beta-isomer) > 5-methylcytosine (alpha-isomer) > 5-iodocytosine (alpha-isomer) > 5-chlorocytosine (beta-isomer). The anti-HIV potency of purine analogues was found to be in the following decreasing order: 2,6-diaminopurine (beta-isomer) > 2-chloroadenine (alpha-isomer) > 2-fluoroadenine (beta-isomer) > adenine (beta-isomer) > 2-amino-6-chloropurine (alpha-isomer) > 2-amino-6-chloropurine (beta-isomer) > guanine (beta-isomer) > 2-fluoroadenine (alpha-isomer) > adenine (alpha-isomer) > 2,6-diaminopurine (alpha-isomer) > N6-methyladenine (beta-isomer). It is interesting to note that the alpha-5-fluorocytosine analogue exhibited an excellent anti-HIV activity (EC50 = 0.063 microM) without cytotoxicity up to 100 microM in PBM cell.

1,3-dioxolanylpurine nucleosides (2R,4R) and (2R,4S) with selective anti-HIV-1 activity in human lymphocytes.

In order to study the structure-activity relationships of dioxolane nucleosides as potential anti-HIV-1 agents, various enantiomers of pure dioxolanylpurine nucleosides were synthesized and evaluated against HIV-1 in human peripheral blood mononuclear cells. The enantiomerically pure key intermediate 1, which was synthesized in nine steps from 1,6-anhydro-beta-D-mannose, was condensed with 6-chloropurine, 6-chloro-2-fluoropurine, and 2,6-dichloropurine in the presence of TMS triflate. The chloro or fluoro substituents were readily converted into amino, N-methylamino, hydroxy, methoxy, thiol, and methylthio under appropriate reaction conditions. Upon evaluation of these dioxolanes, the guanine derivative 24 exhibited the most potent anti-HIV-1 activity without cytotoxicity up to 100 microM in various cells. The decreasing antiviral activity order of beta-isomers was as follows: guanine > 6-chloro-2-aminopurine > 2-fluoroadenine > or = adenine > or = 2,6-diaminopurine > hypoxanthine > 2-chloroadenine > 6-chloropurine approximately equal to N6-methyladenine approximately equal to 6-mercaptopurine approximately equal to 6-(methylthio)purine.

Anthraquinones as a new class of antiviral agents against human immunodeficiency virus.

Various anthraquinones substituted with hydroxyl, amino, halogen, carboxylic acid, substituted aromatic group, and sulfonate were tested to determine their activity against human immunodeficiency virus type 1 (HIV-1) in primary human lymphocytes. Among the compounds tested, polyphenolic and/or polysulfonate substituted anthraquinones were found to possess the most potent antiviral activity. Hypericin, an anthraquinone dimer previously shown to have activity against nonhuman retroviruses also exhibited anti-HIV-1 activity in lymphocytes. the active anthraquinones inhibited HIV-1 reverse transcriptase. However, this enzyme inhibition was selective only for 1,2,5,8-tetrahydroanthraquinone and hypericin. Hypericin interacts nonspecifically with protein suggesting that this effect may dictate its inhibitory activity against the viral reverse transcriptase.

Combinations of isoprinosine and 3'-azido-3'-deoxythymidine in lymphocytes infected with human immunodeficiency virus type 1.

Since clinical trials are being planned with the immunomodulating drug isoprinosine combined with the antiviral drug 3'-azido-3'-deoxythymidine (AZT) in patients with acquired immunodeficiency syndrome (AIDS) and AIDS-related complex, it is important to determine the type of antiviral interaction produced by these drugs in vitro. Such a combined modality may not only produce enhanced antiviral effects but also may have a valuable immunorestorative action. The interaction of several ratios of AZT and isoprinosine on the replication of human immunodeficiency virus type 1 in human peripheral blood mononuclear cells was determined by reverse transcriptase assay of disrupted virus obtained from supernatants of cells that were exposed to virus and the drugs separately and in combination and by a human immunodeficiency virus type 1 p24 enzyme immunoassay of the same supernatants. The correlation between the reverse transcriptase and enzyme immunoassay data was high. The antiviral activity of AZT alone was neither diminished nor augmented when AZT was used in combination with isoprinosine. Isoprinosine did not enhance virus yield when used alone or in combination with AZT in peripheral blood mononuclear cells, nor did it affect the growth of uninfected cells. The in vitro results indicate that this combination did not decrease the efficacy of AZT or exacerbate virus replication.

Activities of 3'-azido-3'-deoxythymidine nucleotide dimers in primary lymphocytes infected with human immunodeficiency virus type 1.

The relative antiviral potencies of five nucleotide heterodimers of 3'-azido-3'-deoxythymidine (AZT), 3'-azido-3'-deoxythymidilyl-(5',5')-2'-3'-dideoxy-5'-adenylic acid (AZT-P-ddA), 3'-azido-3'-deoxythymidilyl-(5',5')-2',3'-dideoxy-5'-inosinic acid (AZT-P-ddI), and the corresponding 2-cyanoethyl congeners AZT-P(CyE)-ddA and AZT-P(CyE)-ddI, were determined in primary human peripheral blood mononuclear cells infected with human immunodeficiency virus type 1. The homodimer 3'-azido-3'-deoxythymidilyl-(5',5')-3'-azido-3'-deoxythymidilic acid (AZT-P-AZT) was also included for comparison. The potencies of the compounds were AZT-P-ddA greater than or equal to AZT-P-ddI greater than AZT-P(CyE)-ddA greater than or equal to AZT-P(CyE)-ddI greater than or equal to AZT greater than AZT-P-AZT. Whereas AZT-P-ddA and AZT-P-ddI had in vitro therapeutic indices greater than that of AZT, the homodimer of AZT had a low therapeutic index. AZT-P-ddI exhibited the lowest toxicity in peripheral blood mononuclear, Vero, or CEM cells. Combination studies between AZT and 2',3'-dideoxyinosine (ddI) at nontoxic concentrations indicated a synergistic interaction at a drug ratio of 1:100. At higher ratios (1:500 and 1:1,000), the interactions were synergistic only at concentrations that produced up to 75% virus inhibition. At higher levels of antiviral effects, this combination was antagonistic, as determined by the multiple drug effect analysis method. AZT-P-ddI was about 10-fold less toxic than AZT to human granulocyte-macrophage progenitor cells. However, no significant difference was apparent when the compounds were evaluated against cells of the erythroid lineage. The greater antiviral activity and lower toxicity of this compound could not be attributed to the extracellular decomposition of the dimer in media at physiological temperature and pH. However, in acidic solutions, AZT-P-ddI decomposed in a pH-dependent manner. Advanced preclinical studies with this heterodimer of two clinically effective antiretroviral agents should be considered.

Characterization of human immunodeficiency viruses resistant to oxathiolane-cytosine nucleosides.

The (-) enantiomers of 2',3'-dideoxy-5-fluoro-3'-thiacytidine [(-)-FTC] and 2',3'-dideoxy-3'-thiacytidine [(-)-BCH-189] were recently shown to inhibit selectively human immunodeficiency viruses (HIV) and hepatitis B virus in vitro. In the current study, the potential for HIV type 1 (HIV-1) resistance to these compounds was evaluated by serial passage of the virus in human peripheral blood mononuclear cells and MT-2 cells in the presence of increasing drug concentrations. Highly drug-resistant HIV-1 variants dominated the replicating virus population after two or more cycles of infection. The resistant variants were cross-resistant to (-)-FTC, (-)-BCH-189, and their (+) congeners but remained susceptible to 2',3'-dideoxycytidine, 3'-azido-3'-deoxythymidine, 3'-fluoro-3'-deoxythymidine, 2',3'-dideoxyinosine, phosphonoformate, the TIBO compound R82150, and the bis(heteroaryl)piperazine derivative U-87201E. Reverse transcriptase derived from drug-resistant viral particles was 15- to 50-fold less susceptible to the 5'-triphosphates of FTC and BCH-189 compared with enzyme from parental drug-susceptible virus. DNA sequence analysis of the reverse transcriptase gene amplified from resistant viruses consistently identified mutations at codon 184 from Met (ATG) to Val (GTG or GTA) or Ile (ATA). Sequence analysis of amplified reverse transcriptase from a patient who had received (-)-BCH-189 therapy for 4 months demonstrated a mixture of the Met-184-to-Val (GTG) mutation and the parental genotype, indicating that the Met-184 mutation can occur in vivo.